Unrecognized selector sent to instance

[anonym24]

When I try to click any button I get the next error:

2019-03-08 02:46:35.189783+0200 YouTubePlayerExample[4824:68717] -[YouTubePlayerExample.ViewController loadVideo:]: unrecognized selector sent to instance 0x7ffb6c005030
2019-03-08 02:46:35.193191+0200 YouTubePlayerExample[4824:68717] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[YouTubePlayerExample.ViewController loadVideo:]: unrecognized selector sent to instance 0x7ffb6c005030'
*** First throw call stack:
(
	0   CoreFoundation                      0x00000001098471bb __exceptionPreprocess + 331
	1   libobjc.A.dylib                     0x0000000107e25735 objc_exception_throw + 48
	2   CoreFoundation                      0x0000000109865f44 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
	3   UIKitCore                           0x000000010c200b4a -[UIResponder doesNotRecognizeSelector:] + 287
	4   CoreFoundation                      0x000000010984bed6 ___forwarding___ + 1446
	5   CoreFoundation                      0x000000010984dda8 _CF_forwarding_prep_0 + 120
	6   UIKitCore                           0x000000010c1d3ecb -[UIApplication sendAction:to:from:forEvent:] + 83
	7   UIKitCore                           0x000000010bc0f0bd -[UIControl sendAction:to:forEvent:] + 67
	8   UIKitCore                           0x000000010bc0f3da -[UIControl _sendActionsForEvents:withEvent:] + 450
	9   UIKitCore                           0x000000010bc0e31e -[UIControl touchesEnded:withEvent:] + 583
	10  UIKitCore                           0x000000010c20f0a4 -[UIWindow _sendTouchesForEvent:] + 2729
	11  UIKitCore                           0x000000010c2107a0 -[UIWindow sendEvent:] + 4080
	12  UIKitCore                           0x000000010c1ee394 -[UIApplication sendEvent:] + 352
	13  UIKitCore                           0x000000010c2c35a9 __dispatchPreprocessedEventFromEventQueue + 3054
	14  UIKitCore                           0x000000010c2c61cb __handleEventQueueInternal + 5948
	15  CoreFoundation                      0x00000001097ac721 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
	16  CoreFoundation                      0x00000001097abf93 __CFRunLoopDoSources0 + 243
	17  CoreFoundation                      0x00000001097a663f __CFRunLoopRun + 1263
	18  CoreFoundation                      0x00000001097a5e11 CFRunLoopRunSpecific + 625
	19  GraphicsServices                    0x0000000111a711dd GSEventRunModal + 62
	20  UIKitCore                           0x000000010c1d281d UIApplicationMain + 140
	21  YouTubePlayerExample                0x00000001074dce27 main + 71
	22  libdyld.dylib                       0x000000010ace0575 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

[anonym24]

I tried to create my own example instead of using existing and it worked